An isotope dilution-thermal ionisation mass spectrometric (ID-TIMS) methodology using enriched235U (>90 at.%) as a spike is described for the determination of trace uranium (U) in plutonium (Pu). The method is based on the monitoring of UO+instead of U+in order to overcome the isobaric interference of238Pu at238U. The present approach obviates the need for the chemical separation of microgram quantities of U from relatively large amounts of Pu. This method is useful for determining decontamination factors during U-Pu chemical separation, and also for determining trace U in a proposed Pu chemical assay reference material. In practice, the U isotopic concentration in the Pu sample must be known for highly accurate results. © 2007 Elsevier B.V. All rights reserved.
Alamelu, D., & Aggarwal, S. K. (2007). A novel method for trace uranium determination in plutonium by thermal ionisation mass spectrometry. Journal of Alloys and Compounds, 444–445(SPEC. ISS.), 640–642. https://doi.org/10.1016/j.jallcom.2007.01.088